1. Field of the Invention
The present invention relates to a mounting tool for attaching a measuring device to a machine tool. In particular, the present invention regards a mounting tool for attaching a linear encoder to a machine tool.
2. Dissussion of Related Art
It is well known to retrofit one or more axes of existing, manually operated machine tools with linear encoders. The linear encoders generate position dependent output signals so that the machine tools can be operated as numerically controlled machines.
An example of a system for retrofitting manually operated machine tools with linear encoders is the bracket kit sold by Acu-Rite of Jamestown, N.Y. under Model No. 385072-17. As shown in FIG. 1, the system 100 includes a linear encoder 102 for attachment to the longitudinal axis 104 of the machine tool 106. As shown in FIG. 2, a reading head 108 is placed adjacent to the bottom of the scale case 110 that contains the linear encoder 102. The reading head 108 is moved so that an alignment mark 112 is aligned with an alignment mark 114 positioned on the scale case 110. Once alignment is achieved, a reading head bracket 116 is attached to the reading head 108 via screws 118 as shown in FIG. 3.
Once the reading head bracket 116 is attached to the reading head 108, the table 120 of the machine tool 106 is positioned at its center of travel. In addition, the linear encoder 102 is centered against the table 120 and the reading head bracket 116 is centered against the saddle 122 of the machine tool 106 as shown in FIGS. 4 and 5.
At this stage, one of the mounting holes 124 of the linear encoder 102 is marked to the back side of the table 120 as shown in FIG. 5. The linear encoder 102 is removed and a hole is drilled at the marked location. After the hole has been drilled, one end of the linear encoder 102 is attached to the table 120 by inserting a screw into both a mounting hole 124 and the drilled hole. The linear encoder 102 is realigned and the other mounting hole 124 is marked. Again, the linear encoder 102 is moved and a hole is drilled at the marked location. The linear encoder 102 is realigned and a screw is inserted through the other mounting hole and the recently drilled hole resulting in the attachment of the linear encoder 102 to the table 120.
At this stage, a center support 121 is attached to the table 120. This attachment is accomplished by placing the center support 121 on top of the scale case 138 at the center of the linear encoder 102. After the scale case 138 is centered, the location of the center support 121 is marked via a transfer punch. The center support 121 is removed and the scale case 138 is covered so that the marked location of the center support is drilled to form a hole. The center support 121 is then replaced and a screw is inserted into the center support 121 and the drilled hole to attach the center support to the table as shown in FIGS. 4 and 5. At this stage, the reading bracket is attached to the saddle 122 via screws 119.
The process for attaching a second linear encoder 126 to the cross-feed installation of the machine tool 106 is even more complicated than that discussed above for linear encoder 102. The end result of the process is for the linear encoder 126 to be attached to the knee 146 of the machine tool 106 via a spar 130 that is attached to the knee 146 via screws as shown in FIG. 6.
The initial part of the attachment process involves moving the reading head 136 along the bottom portion of a scale case 138 that contains the linear encoder 126 until alignment marks 139 and 140 are aligned with one another. An L-shaped reading head bracket 134 with attached mounting block 132 is later attached to the reading head 136 via screws 142 as shown in FIGS. 8 and 10. Once the reading head bracket 134 is attached to the reading head 136, the saddle 144 and attached gib 128 are moved to their center of travel. At this position, the linear encoder 126 is centered against the knee 146 of the machine tool 106 and the mounting block 132 is positioned to the side of the gib 128. Next, both of the mounting holes 148 of the mounting block 132 are marked to the side of the gib 128 as shown in FIG. 8. After marking is complete, the linear encoder 126, mounting block 132 and reading head bracket 136 are removed so that holes are formed at the marked positions.
After the holes are formed, the linear encoder 126 is inserted into the spar 130 as shown in FIG. 9. The mounting block 132 is then attached to the gib 128 by inserting screws through the mounting holes 148 and the holes formed in the gib 128 as shown in FIG. 10. At this stage, a pair of lines is scribed on the knee 146 marking the top and end of the spar 130. The mounting block 132 and the linear encoder 126 are then removed from the saddle.
The spar 130 is then removed from the linear encoder 126 and positioned adjacent to the scribed lines on the knee 146. At this position, the mounting hole 150 nearest the scribed lines is marked to the knee 146. The spar 130 is removed and a hole is drilled at the marked location.
After the hole has been drilled, one end of the spar 130 is attached to the knee 146 by inserting a screw into both a mounting hole 150 and the drilled hole. The spar 130 is attached with a pair of leveling blocks 151 to the knee 146 via set screws. The spar 130 is then realigned and the other mounting hole 150 is marked. Again, the spar 130 is moved and a hole is drilled at the marked location. The spar 130 is realigned and a screw is inserted through the other mounting hole 150 and the recently drilled hole resulting in the attachment of the spar 130 to the knee 146.
After the spar 130 is attached to the knee 146, the linear encoder 126, without mounting block 132 attached thereto, is inserted into the spar 130 and attached thereto via set screws as shown in FIG. 11. The mounting block 132, with reading head bracket 136 attached thereto, is then attached to the gib 128 via screws and is not attached to the linear encoder 126.
In each of the above-described processes, it is necessary to attach and remove the linear encoder and the linear encoder components a number of times to mark and form holes for attachment of the linear encoder. Accordingly, the process of attaching linear encoders to one or more of the machine axes can be a time consuming process.
Accordingly, an object of the present invention is to improve the mounting procedure for linear encoders that are used to retrofit one or more axes of a manually operated machine tool.